A monoclonal antibody designed OC125, has been synthesized against epithelial ovarian cancer. A phase I study has been initiated to investigate iodine 131-labeled OC125 in patients with recurrent ovarian cancer. Twenty sever patients have been treated using an escalating dose schedule. Hematologic toxicity was observed with a dose of 140 mCi iodine-131. Ten patients will be treated at a dose of 130 mCi iodine-131 to obtain the maximum tolerated dose.